Trans-medium blue actually comes first. It seems counterintuitive (after all, in the LEGO color naming system, "medium" is the shade between "light" and "bright", with a few obscure exceptions like Medium Nougat and Medium Lilac), until you realize that the official name for the color isn't Transparent Medium Blue, but actually Transparent Fluorescent Blue.

The roof isn't quite as good looking as it should. Somehow, I couldn't put the plates straight on the beams so I heightened them a bit...
Due to a collision boundary problem, I couldn't place the flame parts in the hearth.
the lamp post doesn't have the right bubble piece
and finally, there's no rope piece to make the fairy lights of the christmas tree.

Oh, I also had to create a replacement part for the white balcony thingy on the second floor

You should insert a link to the image instead then show the image itself inside the the post.
So image will not appear in the post, but it is easily reachable clicking on the link!
Obviously that's only for the "extra image" of the winter town, not for images of official sets.

Differences:
- The 1x16 white bricks (internal-rear area) could not be connected and where replaced with shorter bricks and plates.
- The rudder has been advanced one stud because for some mysterious reason it could not be connected to the roof-tile in the right position.
- Stickers missing

Differences (the list of correct parts would be shorter...)
- Windows, Wheels and Couplings are different because of unavailability of vintage train parts
- The passenger wagons have been elonged two studs in order to insert 1x4 fencing gates as I could not find 1x3 ones.
- The engine and battery box have been simulated with bricks.
- Curved rails and train signals were not available.

Differences:
- The old-style windows have been replaced
- The original set includes no baseplate, it is based on three 10x20 bricks, which are replaced by smaller bricks; the baseplates are needed to keep bricks together.
- The "Legologo" flag is missing.

You should insert a link to the image instead then show the image itself inside the the post.
So image will not appear in the post, but it is easily reachable clicking on the link!
Obviously that's only for the "extra image" of the winter town, not for images of official sets.

oh, ok

but they're still official sets, I just put them in a single file to make them look good...

Someday, the whole Universe shall bow before my genius... or at least the cat... maybe...

None of the prints are available. All the parts that should have prints have been left blank.

The black 2x6x7 door frame (part 4071) and the corresponding dark gray jail door (part 4611) are not available in LDD. They have been left out of the model.

The two blue banners and two wings, all plastic film pieces, are not available in LDD and have been left out of the model.

The white 2x8x6 revolving wall frame (part 30101) and black revolving wall (part 30102) are not available in LDD and have been left out of the model.

Lastly, the instructions do not designate one correct way to assemble the fortress sections. The file represents option one of the two recommended options, and the sections are grouped to allow for easy reassembly into any other configuration.

Feel free to point out any errors I've missed, and I will try to correct them.

None of the prints are available. All the parts that should have prints have been left blank.

An additional cape piece, piece 4524, is included in the set but not pictured anywhere in the instructions. It has been left to the side of the model.

Feel free to point out any errors I've missed, and I will try to correct them.

The set actually comes with two heads for the guy in yellow, the second head has a red mask over his eyes and that's what the cape is for. Sort of a Super Man-esque costume. I don't think it was anywhere on the box or instructions, but I did check the peeron inventory just to make sure I remembered correctly (I have the set XD) and it confirmed it. The back of the box has a funny picture of him, too, which you can see here, if you so fancy.

The set actually comes with two heads for the guy in yellow, the second head has a red mask over his eyes and that's what the cape is for. Sort of a Super Man-esque costume. I don't think it was anywhere on the box or instructions, but I did check the peeron inventory just to make sure I remembered correctly (I have the set XD) and it confirmed it. The back of the box has a funny picture of him, too, which you can see here, if you so fancy.

Lol, I know about the superhero suit-- I had the LEGO Loco computer game and found the little easter eggs like changing the station master into the superhero form to be some of the cutest things about it. That, and Gribbit the frog.

But I had overlooked that this set had a "normal", non-masked head alongside it. I had the Bricklink inventory open, but obviously didn't check thoroughly enough! Regardless, I'll update this with the extra head to the side ASAP (not that it's a major issue since it doesn't actually appear in the build).

Lol, I know about the superhero suit-- I had the LEGO Loco computer game and found the little easter eggs like changing the station master into the superhero form to be some of the cutest things about it. That, and Gribbit the frog.

But I had overlooked that this set had a "normal", non-masked head alongside it. I had the Bricklink inventory open, but obviously didn't check thoroughly enough! Regardless, I'll update this with the extra head to the side ASAP (not that it's a major issue since it doesn't actually appear in the build).

I loved all the little easter eggs in Loco, too. Finding those was almost half the fun.

I wasn't sure whether or not to even post about the head (especially since the only real purpose was for the alternate print - which doesn't matter so much in LDD because they don't have it anyways!), but figured I'd mention it just in case.

I found myself in a Creator mood yesterday and today, and so undertook building some of the alternate models for sets already created by other builders. I hope that's OK, since they're not really updated versions of other builders' models but rather entirely different models with the same set number.

First, I have version one of 4956 House from the Creator theme. Calabar already built version two.

No errors on this one. On a side note, I built this using Creator mode rather than Universe mode (since this is one of the sets whose entire brick palette can be filtered out of Creator mode's brick palette).

This one does have an error. While it was infuriating to assemble the climbing plants on version one, here it would have been impossible. The placement of the plants requires the individual pieces to bend in order to be placed correctly-- the inner layer of leaf pieces cannot fit between the outer layer and the wall otherwise.

Third, version two of 4996 Beach House from the Creator theme. In this case, Calabar already built version one.

Again, no errors. Creator sets seem to have some of the strictest adherence to the use of legal connections, if these models are any evidence. They're also very compatible with LEGO Digital Designer due to their use of basic bricks and basic colors.

In addition, here's a little impulse set I've been neglecting to post, which I've finally got on my Brickshelf: 2886 Formula 1 Racing Car from the Race theme. It's completely identical to set 1088 Road Burner from the Extreme Team theme, so it might ought to be indexed as both.

ERRORS:
-Minifigure torsos and heads are approximations. Can't find exact printings.
-Soldier's hat is an approximation (can't color/decorate the plume part).
-Brick 3068 should have a particular printed pattern on it of a treasure map. The exact pattern does not exist in LDD as of version 4.0. A different but similar printing is used instead.

The thing I notice is that several colors are incorrect. If you compare to AndyC's model, you can see where you have used the wrong colors (Download Andys model and paste it next to yours and start comparing).

In general, to find which the colors are supposed to be in an official set a good idea is to use BrickLink. In this case you would have this part list.

So how do you know which color is which in LDD? This has been explained before here at forum, for example this post by Aanchir.

One error: due to part of the car not being "in system", the front and rear bumper (as well as the headlights and taillights) cannot be attached to the little truck.

It never cease to surprise me the way official sets breaks the rules. Seems we have a whole bunch of examples now, even from very recent sets

Anyway, I like the way you use the term "in system", which is as far as I know the term TLG use.

Another intresting example of elements being not being in system (and then becoming in system) is these two (see pic). The red one (4623) is the old one, that will be phased out. It is not in system, since the hook is placed a bit too far out. The green one (88072) is the new one. This one is in system since the hook is inline. BrickLink does not make a distinction between the two which may cause problems for brick buyers/builders.

Side note: As can be seen LDD incorrectly accepts the connection between the 1x1 plate with clip and the 4623.

6745 - Propellor Power - Model 3 - Creator
(the main model has already been shared)problem not fixed in LDD4: the main model could be fixed in LDD4; in my opinion, this is not a problem in LDD but in the model itself because I tested it in Ldraw too and there where not enough space, so that the axle would be stressed by overflexing.

Errors:
Like in the main model, the turbine seems not to have enough internal space to let 2stud-wide plates pass through it, as required in the real model; so the plate has been "trimmed".
I shall report that to the Bugs topic.

6747 - Race Riders - CreatorThe missing part ("front fork") is now available on LDD4 and the model has been updated.

Errors:
The only one error is the missing part "Technic Motorcycle pivot", which has been built in a different way; unfortunately I was not able to reproduce all the connections and shoud replace other parts; in detail:
1 x "Connector peg w. friction 3M" in place of 1 x "Connector peg w. friction" (centre, vertically)
2 x "Connector peg / cross axle" in place of 1 x "Cross axle 5m" (horizontally, because the replaced piece has no central hole)